Operations with Integers | FIO

Question 25

Fill in the blanks in at least 5 different ways with integers:

(a) +×=36\square + \square \times \square = -36

(b) ()×=12(\square - \square) \times \square = 12

(c) (())=1(\square - (\square - \square)) = -1

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Solution

We need to find different sets of integers to make each equation true.

Step 1 — Understanding the first equation

The first equation is +×=36\square + \square \times \square = -36. Let us call the numbers in the blanks aa, bb, and cc. So, the equation is a+b×c=36a + b \times c = -36. Remember the order of operations: multiplication happens before addition. This means we first calculate b×cb \times c, then add aa to that result. So, a+(b×c)a + (b \times c) must equal -36.

Step 2 — Finding integers for (a) - Way 1

Let us choose values for bb and cc. We will choose bb as -6 and cc as 6. First, we multiply bb and cc.

b×c=(6)×6b \times c = (-6) \times 6

=36= -36

Now, we need to find aa such that a+(36)=36a + (-36) = -36. To find aa, we add 36 to both sides.

a=36(36)a = -36 - (-36)

=36+36= -36 + 36

=0= 0

So, the numbers are 0, -6, and 6. Let us check this in the original equation.

0+(6)×6=0+(36)0 + (-6) \times 6 = 0 + (-36)

0+(6)×6=36\boxed{0 + (-6) \times 6 = -36}

Step 3 — Finding integers for (a) - Way 2

Let us choose bb as -5 and cc as 8. First, we multiply bb and cc.

b×c=(5)×8b \times c = (-5) \times 8

=40= -40

Now, we need to find aa such that a+(40)=36a + (-40) = -36. To find aa, we add 40 to both sides.

a=36(40)a = -36 - (-40)

=36+40= -36 + 40

=4= 4

So, the numbers are 4, -5, and 8. Let us check this in the original equation.

4+(5)×8=4+(40)4 + (-5) \times 8 = 4 + (-40)

4+(5)×8=36\boxed{4 + (-5) \times 8 = -36}

Step 4 — Finding integers for (a) - Way 3

Let us choose bb as -8 and cc as 4. First, we multiply bb and cc.

b×c=(8)×4b \times c = (-8) \times 4

=32= -32

Now, we need to find aa such that a+(32)=36a + (-32) = -36. To find aa, we add 32 to both sides.

a=36(32)a = -36 - (-32)

=36+32= -36 + 32

=4= -4

So, the numbers are -4, -8, and 4. Let us check this in the original equation.

4+(8)×4=4+(32)-4 + (-8) \times 4 = -4 + (-32)

4+(8)×4=36\boxed{-4 + (-8) \times 4 = -36}

Step 5 — Finding integers for (a) - Way 4

Let us choose bb as -8 and cc as 6. First, we multiply bb and cc.

b×c=(8)×6b \times c = (-8) \times 6

=48= -48

Now, we need to find aa such that a+(48)=36a + (-48) = -36. To find aa, we add 48 to both sides.

a=36(48)a = -36 - (-48)

=36+48= -36 + 48

=12= 12

So, the numbers are 12, -8, and 6. Let us check this in the original equation.

12+(8)×6=12+(48)12 + (-8) \times 6 = 12 + (-48)

12+(8)×6=36\boxed{12 + (-8) \times 6 = -36}

Step 6 — Finding integers for (a) - Way 5

Let us choose bb as 3 and cc as -11. First, we multiply bb and cc.

b×c=3×(11)b \times c = 3 \times (-11)

=33= -33

Now, we need to find aa such that a+(33)=36a + (-33) = -36. To find aa, we add 33 to both sides.

a=36(33)a = -36 - (-33)

=36+33= -36 + 33

=3= -3

So, the numbers are -3, 3, and -11. Let us check this in the original equation.

3+3×(11)=3+(33)-3 + 3 \times (-11) = -3 + (-33)

3+3×(11)=36\boxed{-3 + 3 \times (-11) = -36}

Step 7 — Understanding the second equation

The second equation is ()×=12(\square - \square) \times \square = 12. Let us call the numbers in the blanks xx, yy, and zz. So, the equation is (xy)×z=12(x - y) \times z = 12. Remember the order of operations: we first calculate inside the parenthesis (xy)(x - y). Then we multiply that result by zz. The product of (xy)(x - y) and zz must be 12. This means zz must be a factor of 12.

Step 8 — Finding integers for (b) - Way 1

Let us choose a value for zz. We will choose zz as 1. Now, we need (xy)×1=12(x - y) \times 1 = 12. This means (xy)(x - y) must be 12. We need two numbers xx and yy whose difference is 12. Let us choose yy as 1. Then x1=12x - 1 = 12. To find xx, we add 1 to both sides.

x=12+1x = 12 + 1

=13= 13

So, the numbers are 13, 1, and 1. Let us check this in the original equation.

(131)×1=12×1(13 - 1) \times 1 = 12 \times 1

(131)×1=12\boxed{(13 - 1) \times 1 = 12}

Step 9 — Finding integers for (b) - Way 2

Let us choose zz as 2. Now, we need (xy)×2=12(x - y) \times 2 = 12. To find (xy)(x - y), we divide 12 by 2.

xy=12÷2x - y = 12 \div 2

=6= 6

We need two numbers xx and yy whose difference is 6. Let us choose yy as 4. Then x4=6x - 4 = 6. To find xx, we add 4 to both sides.

x=6+4x = 6 + 4

=10= 10

So, the numbers are 10, 4, and 2. Let us check this in the original equation.

(104)×2=6×2(10 - 4) \times 2 = 6 \times 2

(104)×2=12\boxed{(10 - 4) \times 2 = 12}

Step 10 — Finding integers for (b) - Way 3

Let us choose zz as -6. Now, we need (xy)×(6)=12(x - y) \times (-6) = 12. To find (xy)(x - y), we divide 12 by -6.

xy=12÷(6)x - y = 12 \div (-6)

=2= -2

We need two numbers xx and yy whose difference is -2. Let us choose yy as 3. Then x3=2x - 3 = -2. To find xx, we add 3 to both sides.

x=2+3x = -2 + 3

=1= 1

So, the numbers are 1, 3, and -6. Let us check this in the original equation.

(13)×(6)=(2)×(6)(1 - 3) \times (-6) = (-2) \times (-6)

(13)×(6)=12\boxed{(1 - 3) \times (-6) = 12}

Step 11 — Finding integers for (b) - Way 4

Let us choose zz as 3. Now, we need (xy)×3=12(x - y) \times 3 = 12. To find (xy)(x - y), we divide 12 by 3.

xy=12÷3x - y = 12 \div 3

=4= 4

We need two numbers xx and yy whose difference is 4. Let us choose yy as 10. Then x10=4x - 10 = 4. To find xx, we add 10 to both sides.

x=4+10x = 4 + 10

=14= 14

So, the numbers are 14, 10, and 3. Let us check this in the original equation.

(1410)×3=4×3(14 - 10) \times 3 = 4 \times 3

(1410)×3=12\boxed{(14 - 10) \times 3 = 12}

Step 12 — Finding integers for (b) - Way 5

Let us choose zz as 4. Now, we need (xy)×4=12(x - y) \times 4 = 12. To find (xy)(x - y), we divide 12 by 4.

xy=12÷4x - y = 12 \div 4

=3= 3

We need two numbers xx and yy whose difference is 3. Let us choose yy as 13. Then x13=3x - 13 = 3. To find xx, we add 13 to both sides.

x=3+13x = 3 + 13

=16= 16

So, the numbers are 16, 13, and 4. Let us check this in the original equation.

(1613)×4=3×4(16 - 13) \times 4 = 3 \times 4

(1613)×4=12\boxed{(16 - 13) \times 4 = 12}

Step 13 — Understanding the third equation

The third equation is (())=1(\square - (\square - \square)) = -1. Let us call the numbers in the blanks pp, qq, and rr. So, the equation is (p(qr))=1(p - (q - r)) = -1. Remember the order of operations: we always work from the innermost parenthesis first. First, we calculate (qr)(q - r). Then we subtract this result from pp. The final result must be -1.

Step 14 — Finding integers for (c) - Way 1

Let us choose values for qq and rr. We will choose qq as 10 and rr as 4. First, we calculate (qr)(q - r).

qr=104q - r = 10 - 4

=6= 6

Now, we need to find pp such that p6=1p - 6 = -1. To find pp, we add 6 to both sides.

p=1+6p = -1 + 6

=5= 5

So, the numbers are 5, 10, and 4. Let us check this in the original equation.

(5(104))=56(5 - (10 - 4)) = 5 - 6

(5(104))=1\boxed{(5 - (10 - 4)) = -1}

Step 15 — Finding integers for (c) - Way 2

Let us choose qq as 3 and rr as 2. First, we calculate (qr)(q - r).

qr=32q - r = 3 - 2

=1= 1

Now, we need to find pp such that p1=1p - 1 = -1. To find pp, we add 1 to both sides.

p=1+1p = -1 + 1

=0= 0

So, the numbers are 0, 3, and 2. Let us check this in the original equation.

(0(32))=01(0 - (3 - 2)) = 0 - 1

(0(32))=1\boxed{(0 - (3 - 2)) = -1}

Step 16 — Finding integers for (c) - Way 3

Let us choose qq as 1 and rr as 1. First, we calculate (qr)(q - r).

qr=11q - r = 1 - 1

=0= 0

Now, we need to find pp such that p0=1p - 0 = -1. This means pp must be -1.

p=1p = -1

So, the numbers are -1, 1, and 1. Let us check this in the original equation.

(1(11))=10(-1 - (1 - 1)) = -1 - 0

(1(11))=1\boxed{(-1 - (1 - 1)) = -1}

Step 17 — Finding integers for (c) - Way 4

Let us choose qq as 0 and rr as 4. First, we calculate (qr)(q - r).

qr=04q - r = 0 - 4

=4= -4

Now, we need to find pp such that p(4)=1p - (-4) = -1. Remember that subtracting a negative number is the same as adding a positive number. So, p+4=1p + 4 = -1. To find pp, we subtract 4 from both sides.

p=14p = -1 - 4

=5= -5

So, the numbers are -5, 0, and 4. Let us check this in the original equation.

(5(04))=5(4)(-5 - (0 - 4)) = -5 - (-4)

=5+4= -5 + 4

(5(04))=1\boxed{(-5 - (0 - 4)) = -1}

Step 18 — Finding integers for (c) - Way 5

Let us choose qq as -5 and rr as 4. First, we calculate (qr)(q - r).

qr=54q - r = -5 - 4

=9= -9

Now, we need to find pp such that p(9)=1p - (-9) = -1. Remember that subtracting a negative number is the same as adding a positive number. So, p+9=1p + 9 = -1. To find pp, we subtract 9 from both sides.

p=19p = -1 - 9

=10= -10

So, the numbers are -10, -5, and 4. Let us check this in the original equation.

(10(54))=10(9)(-10 - (-5 - 4)) = -10 - (-9)

=10+9= -10 + 9

(10(54))=1\boxed{(-10 - (-5 - 4)) = -1}

Answer

(a) [ ] + [ ] x [ ] = -36 (i) 0 + (-6) x 6 = -36 (ii) 4 + (-5) x 8 = -36 (iii) -4 + (-8) x 4 = -36 (iv) 12 + (-8) x 6 = -36 (v) -3 + 3 x (-11) = -36

(b) ([ ] - [ ]) x [ ] = 12 (i) (13 - 1) x 1 = 12 (ii) (10 - 4) x 2 = 12 (iii) (1 - 3) x (-6) = 12 (iv) (14 - 10) x 3 = 12 (v) (16 - 13) x 4 = 12

(c) ([ ] - ([ ] - [ ])) = -1 (i) (5 - (10 - 4)) = -1 (ii) (0 - (3 - 2)) = -1 (iii) (-1 - (1 - 1)) = -1 (iv) (-5 - (0 - 4)) = -1 (v) (-10 - (-5 - 4)) = -1

More questions in FIO

Q1

Let us try to find a few more pairs of numbers from their sums and differences:

(a) Sum = 27, Difference = 9

(b) Sum = 4, Difference = 12

(c) Sum = 0, Difference = 10

(d) Sum = 0, Difference = -10

(e) Sum = -7, Difference = -1

(f) Sum = -7, Difference = -13

Q2

Using the token interpretation, find the values of:

(a) 3×(2)3 \times (-2)

(b) (5)×(2)(-5) \times (-2)

(c) (4)×(1)(-4) \times (-1)

(d) (7)×3(-7) \times 3

Q3

If 123×456=56088123 \times 456 = 56088, without calculating, find the value of:

(a) (123)×456(-123) \times 456

(b) (123)×(456)(-123) \times (-456)

(c) (123)×(456)(123) \times (-456)

Q4

Try to frame a simple rule to multiply two integers.

Consider the numbers represented by the following tokens in the diagram:

Q5

Find the following products.

(a) 4×(3)4 \times (-3)

(b) (6)×(3)(-6) \times (-3)

(c) (5)×(1)(-5) \times (-1)

(d) (8)×4(-8) \times 4

(e) (9)×10(-9) \times 10

(f) 10×(17)10 \times (-17)

Q6

Find the values of:

(a) 14×(15)14 \times (-15)

(b) 16×(5)-16 \times (-5)

(c) 36÷(18)36 \div (-18)

(d) (46)÷(23)(-46) \div (-23)

Q7

A freezing process requires that the room temperature be lowered from 32C32^\circ\text{C} at the rate of 5C5^\circ\text{C} every hour. What will be the room temperature 10 hours after the process begins?

Q8

A cement company earns a profit of ₹8 per bag of white cement sold and a loss of ₹5 per bag of grey cement sold. [Represent the profit/loss as integers.]

(a) The company sells 3,000 bags of white cement and 5,000 bags of grey cement in a month. What is its profit or loss? (b) If the number of bags of grey cement sold is 6,400 bags, what is the number of bags of white cement the company must sell to have neither profit nor loss?

Q9

Replace the blank with an integer to make a true statement.

(a) (3)×=27(-3) \times \underline{\quad\quad} = 27

(b) 5×=(35)5 \times \underline{\quad\quad} = (-35)

(c) ×(8)=(56)\underline{\quad\quad} \times (-8) = (-56)

(d) ×(12)=132\underline{\quad\quad} \times (-12) = 132

(e) ÷(8)=7\underline{\quad\quad} \div (-8) = 7

(f) ÷12=11\underline{\quad\quad} \div 12 = -11

Q10

Find the values of the following expressions: (a) (5)×(18+(3))(-5) \times (18 + (-3)) (b) (7)×4×(1)(-7) \times 4 \times (-1) (c) (2)×(1)×(5)×(3)(-2) \times (-1) \times (-5) \times (-3)

Q11

Find the values of the following expressions:

(a) (27)÷9(-27) \div 9

(b) 84÷(4)84 \div (-4)

(c) (56)÷(2)(-56) \div (-2)

Q12

Find the integer whose product with (1)(-1) is:

(a) 27

(b) -31

(c) -1

(d) 1

(e) 0

Q13

If 4756+148+28+5=447 - 56 + 14 - 8 + 2 - 8 + 5 = -4, then find the value of 47+5614+82+85-47 + 56 - 14 + 8 - 2 + 8 - 5 without calculating the full expression.

Q14

Do you remember the Collatz Conjecture from last year? Try a modified version with integers. The rule is — start with any number; if the number is even, take half of it; if the number is odd, multiply it by 3-3 and add 1; repeat. An example sequence is shown below.

Try this with different starting numbers: (21)(-21), (6)(-6), and so on. Describe the patterns you observe.

Q15

In a test, (+4) marks are given for every correct answer and (-2) marks are given for every incorrect answer.

(a) Anita answered all the questions in the test. She scored 40 marks even though 15 of her answers were correct. How many of her answers were incorrect? How many questions are in the test?

(b) Anil scored (-10) marks even though he had 5 correct answers. How many of his answers were incorrect? Did he leave any questions unanswered?

Q16

Pick the pattern — find the operations done by the machine shown below.

Q17

Imagine you're in a place where the temperature drops by 5°C each hour. If the temperature is currently at 8°C, write an expression which denotes the temperature after 4 hours.

Q18

Find 3 consecutive numbers with a product of (a) -6, (b) 120.

Q19

An alien society uses a peculiar currency called 'pibs' with just two denominations of coins — a+13 pibs coin and a -9 pibs coin. You have several of these coins. Is it possible to purchase an item that costs +85 pibs?

Q20

Find the values of:

(a) (32×(18))÷((36))(32 \times (-18)) \div ((-36))

(b) (32)÷((36)×(18))(32) \div ((-36) \times (-18))

(c) (25×(12))÷((45)×(27))(25 \times (-12)) \div ((45) \times (-27))

(d) (280×(7))÷((8)×(35))(280 \times (-7)) \div ((-8) \times (-35))

Q21

Arrange the expressions given below in increasing order:

(a) (348)+(1064)(-348) + (-1064)

(b) (348)(1064)(-348) - (-1064)

(c) 348(1064)348 - (-1064)

(d) (348)×(1064)(-348) \times (-1064)

(e) 348×(1064)348 \times (-1064)

(f) 348×964348 \times 964

Q22

Given that (548)×972=532656(-548) \times 972 = -532656, write the values of:

(a) (547)×972(-547) \times 972

(b) (548)×971(-548) \times 971

(c) (547)×971(-547) \times 971

Q23

Given that 207×(33+7)=5382207 \times (-33 + 7) = -5382, write the value of 207×(337)=___?-207 \times (33 - 7) =\_\_\_?

Q24

Use the numbers 3,2,5,63, -2, 5, -6 exactly once and the operations '+', '-', and 'x' exactly once and brackets as necessary to write an expression such that —

(a) the result is the maximum possible

(b) the result is the minimum possible

Q25

Fill in the blanks in at least 5 different ways with integers:

(a) +×=36\square + \square \times \square = -36

(b) ()×=12(\square - \square) \times \square = 12

(c) (())=1(\square - (\square - \square)) = -1

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